How to Cut a Hole in a Concrete Foundation
A hammer drill is designed to drill holes in masonry and concrete using a masonry drill bit or hole saw. This type of drill creates a jack-hammer–like action to allow better penetration. For small holes, such as if you need to run a wire through the foundation, the masonry bit alone will work.
To cut a hole big enough for a pipe, you will need to use a masonry hole saw, which fits over a specially designed drill bit and is used for holes ranging from ½ inch to 3 ¼ inches. Larger sizes are available but require industrial equipment. Tools for this project can be purchased at most hardware stores or online.
Things You Will Need
- Concrete hole saw
- Hammer drill
- Safety goggles
- Chisel and hammer, optional
Mark on the foundation where you will be drilling the hole. Draw a circle the exact diameter of the desired hole and mark the center. If possible, double check your house plans to ensure no electrical wiring or utilities run through this area.
Use a masonry drill bit to drill a guide hole half way between the top of your circle and the center. Drilling off center will ensure that the drill bit for the hole saw still has good purchase once you begin cutting the hole. Drill bits can be purchased in lengths up to 18 inches to accommodate the thickness of most residential foundations.
Measure the distance between the guide hole and the center of your hole. Use this measurement to mark the center of your hole on the other side of the foundation.
Attach the concrete hole saw to the drill bit. Most hole saw kits come with a standard drill bit and interchangeable saw heads that snap on.
Line up the drill bit with the center of your hole. Press the saw bit firmly into the wall and start drilling slowly to allow the teeth to grip the concrete. The hole saw will create debris within the cut. To make drilling smoother, periodically remove the hole saw to clear debris.
If the thickness of your foundation is greater than the depth of the hole saw, you can use a chisel and hammer to remove some of the drilled concrete core before continuing to drill.
Place the drill bit on the center mark that you made in Step 3 and finish drilling the hole. Push the core out of the hole.
A shop vac is an excellent way to remove chiseled debris.
Always wear safety goggles when drilling concrete.
Adjust the handle at the front of your hammer drill to a 90 degree angle, so if the drill bit becomes stuck, the body of the drill will kick into a closed hand rather than tearing free and causing serious injury.